The use of above-ground watering systems, particularly in dry climates such as the southwestern regions of the United States and in the Mediterranean regions of Europe, the Middle East, and Africa, brings with it a list of known problems. In addition to water loss through evaporation during the watering process, if watering is provided too lightly, shallow plant rooting results. Additionally, repeated surface applications of water tend to produce the buildup of mineral salts, which are detrimental to healthy plant growth.
As increasing population pressures result in greater demands upon fresh water supplies, the benefits of underground irrigation have become increasingly attractive. Such systems place water almost directly into the plant root zone and eliminate evaporative water losses. Their protected location also minimizes the risk of damage from surface activities.
The subsurface fluid distribution system described in my previous patent, Sipaila, U.S. Pat. No. 5,921,711, provides such a subterranean system with reserve fluid storage capacity to maintain soil dampness as well as replace water taken up by plants. As used in a passive subsurface irrigation system, capillary physics and gravity are relied upon to deliver water and nutrients to plants through an interconnected series of chambers and pans. Such systems are capable of reducing the amount of irrigation water required by 50-80% over the more traditional above-ground systems.
As is typical for such systems, the leaching chamber has sloped sidewalls that extend to a curved, arched top. When installed, such extended-arch chambers must resist both top and side loadings. The slots in the sidewalls permit the transport of water from within, but act to weaken the sidewall structure.
While thickening the sidewall would provide additional strength, it also results in an increase in the amount of material required—which is a polyolefin, and is thus tied to the rising cost of petrochemicals. In addition, the added weight of the resulting product adds to the cost of transporting the chambers to the installation site. Also, while it is vital that such chambers are able to efficiently stack for transport, the stacking of such bulked-up chamber walls must not result in forcing the sidewalls out, resulting in the overall flattening and weakening of the arch-shaped chamber.
It thus is desirable to provide additional solutions that increase the structural integrity of the arched chamber in a manner that enhances the operational efficiency and is not negated by increased transportation costs or product damage during shipment.